OBJECTIVES: The major objective of the current investigation is to define the mechanism(s) by which polypeptide hormones regulate synthesis of specific proteins in their target tissues. Several model systems have been developed or adapted in which polypeptide hormones or bioamines appear to increase synthesis of a specific well characterized protein. Using these model systems, experiments are designed to resolve: 1) Whether polypeptide hormones or bioamines regulate protein synthesis by acting at a transcriptional and/or post-transcriptional site. Quantitation of the hormone-induced alterations in intracellular levels of mRNA coding for specific proteins is being attempted to further define the site of regulation. 2) Possible mechanisms by which hormones may regulate protein synthesis at the level of mRNA translation. The functional significance of cAMP-dependent phosphorylation of specific initiation factors is being evaluated. 3) The time course and putative mechanisms by which hormones regulate the apparent transcription of specific mRNAs. RESEARCH GOALS FOR THE COMING YEAR: Studies during the coming year will be directed toward: 1) Further characterization of the primary cultures of parotid cell and hormonal regulation of alpha-amylase biosynthesis in those cultures. 2) Documentation of authenticity of the putative translation product of alpha-amylase mRNA translation. 3) Purification of prolactin and growth hormone mRNAs, and definition of the site and mechanism by which preprolactin is converted to prolactin. 4) Study of functional significance of phosphorylation of specific initiation factors.